Continuous reduction in size of semiconductor devices is dependent upon more precise control of, for instance, the flow and temperature of process gases delivered to a semiconductor process chamber. Typically, in a cross-flow process chamber, a process gas may be delivered to the chamber and directed across the surface of a substrate to be processed. The temperature of the process gas may be controlled by, for example, a pre-heat ring, which surrounds the substrate support.
Controlling flow characteristics and temperature of process gases is critical to obtain, for example, uniform deposition of a layer atop a substrate. Unfortunately, a process gas entering conventional cross-flow process chambers is typically not heated uniformly. In some instances, the chamber walls may act as a heat sink, thus reducing effectiveness of, for example, the pre-heat ring in uniformly heating the process gas prior to deposition on the substrate. Further, the flow direction and velocity of the process gas may be non-uniform proximate the substrate edge. Consequently, these non-uniform temperature and flow characteristics result in non-uniform deposition of a layer proximate the substrate edge.
Accordingly, there is a need in the art for a processing apparatus having improved control of temperature and flow characteristics of a process gas.